Fate Grand X-Over
by The Kingdom of Ruby Luxuria
Summary: In one world, a pair of Master and Servant saved the world from destruction. In another, A Beast-class Servant possessed someone and destroyed the world, recreating it as she sees fit. Now, two pairs of Masters and Servants will have to work together through 20 different singularities in order to stop the Beast herself and revived the dead world...


**Different Reality**

A/N: Yes, this is a reboot, and is officially have nothing to do with Fate DxD Order. This story will be set after Part 1.5 instead of Part 1. Also, the OVAs are canon here . Also, AU. Also, sorry for any mistake in anything, and bad writing.

"Senpai?"

A glasses-wearing purple-haired woman; wearing white jacket over her black sleeveless shirt and red tie around her neck, walks through the corridor of Chaldea, as her heads move all over the place, looking for someone.

Her head keeps moving all over the place, and eventually being called out by a female voice, "Who are you looking for, Mashu?"

The girl quickly turns around toward the owner of the voice, seeing a dark brown-haired female in red and blue outfit, smiling at her.

"da Vinci-san, I was looking for Senpai. Have you seen him?"

"Ritsuka?" the female mutters as she wonders of something, "I did, but he is acting a bit strange before."

"Strange?" Mashu tilts her head in confusion.

"Yeah. I just saw him walking toward that unused room at the back. I was so sure it was locked before."

"I see," the purple-haired girl nods, "I think I know which place he had gone to."

She quickly rushes toward one direction in a hurry.

Xxxxxxxxxxxxxxxx

A black-haired male in white uniform walks toward a door, pushing the door lightly, and enters a dark room with the only place lighten up is the middle of the room; a huge table.

"Ah, welcome back," a pink-haired man greets him from the table.

The male waves at him in confusion, "Doctor Roman? Were you the one who contacted me?"

"No," an orange-haired girl appears before him, grabbing his hand and pulling him toward the table, "It was me."

"Wh-who are you?" the young man questions her.

He turns to the side, noticing a silver-haired girl in black and orange outfit sitting not far from where he was headed to, "Her name is Ritsuka Fujimaru."

"Wha-" the black-haired male is confused, "But that's my name, director."

The white-haired female stares at him, "I think at this point you would have known the purpose of this place; the Lost Room."

The male Ritsuka nods, sitting right beside the female Ritsuka, "Yeah, it's a room that somehow connects with Chaldea from different times, right? The fact that you two are still here…"

The black-haired young man pauses abruptly; looking down with his face seems regretful.

"Thanks for the spoiler," the 'director' mutters in annoyance, "But that's not exactly what this room does. Sure, it can bring people from different points of time together under the same roof, but the same can be said with Servant summoning that Chaldea uses. No, the Lost Room works on a more complicated level."

Roman explains, "The reason why this room was sealed is due to the numerous amount of uncertainty. This room was originally a normal lounge for the staff members, but during one of our research, an accident happened during an experiment with rayshift. This room is now a prototype rayshift machine, capable of connecting Chaldea from different times and even alternate realities."

"Alternate… realities?" the male Ritsuka looks really confused with that term.

The female Ritsuka quickly responds toward him, "Think of it this way. What did you ate for breakfast today?"

"Today?' the male one tries hard to think of the answer, "I believed I ate a bowl of cereal, perhaps?"

"Perhaps?" the silver-haired lady is clearly pissed, "Don't you even remember what you ate today?"

"D-don't be mad at me…" the black-haired male mutters, "I didn't finish my breakfast. Mashu dragged me with all the paperwork about the Clock Tower's visit."

"C-Clock Tow-" the lady is now choking herself in shock as she shakes her head and sighs, "F-forget it…"

The orange-haired girl beside him chuckles, as she now speaks up, "You were busy, right? You could not finish that food since Mashu made you worked so hard. But, in one reality, you did finish your bowl, and had a satisfying morning."

She then winks one of her eyes, "That is how alternate realities work. Stories of your life may be different in some other stories. One world you are working with a magi organization in protecting the human order, but in another you are just a normal man without the knowledge of magecraft. One world you are dating a tsundere girl, in another you are sleeping with her sexier little sister, and in another you and your blonde waifu got cockblocked by a cup."

What is she…?

The girl continues, "In one world, you are a boy, but in another, you are a girl."

Wha-?

Wait…

The male Ritsuka has his eyes widen, "Y-you- You are?"

Roman smiles, "Yes, basically this is what the Lost Room supposed to be, though there are still mysteries this room seem to have possessed."

"Wait," the male Ritsuka turns toward him, "Is she why I was called here?"

"Yes," the director mutters, "Alternate realities are separated from boundaries set by Gaia and Alaya, and only those who know Second Magic can cross those boundaries. But, Chaldea is different. With the combination of magecraft and science, we are capable of reaching other times, and even other realities at some point, even if our body is still here. That is already an accomplishment any magus would want to have."

Alternate reality… Ah, Ritsuka thoughts to himself. The adventure in Shimosa proves just that, as they are going to a different reality instead of back to the past… Are the Singularities can be considered those as well? Probably…

Magecraft are confusing sometimes…

The director continues, "Unfortunately, some realities aren't as happy as others. The usage of LAPLACE, CHALDEAS, SHEBA, TRISMEGISTUS and especially FATE are being violated by unwanted parties. The threat can be as small as exposing futures unnecessarily to the world being implode, and the latter is why we are calling you right now."

Ritsuka is about to respond, but a voice stops him from doing so.

"Senpai?"

He quickly turns to his back, seeing Mashu entering the room as she looks around the place, "Senpai, what are you doing here in this p-"

Her eyes widen as she quickly runs forward toward the table, "D-Director Olga! Dr. Roman! Y-you two…"

The female Ritsuka seems shocked, seeing her as she loses her smiles, but then she smiles back for some reason.

Roman quickly shakes his head, "I'm sorry, Mashu, but we are not from your time; perhaps not even from the same reality."

The purple-haired girl is startled as she pulls herself away before looking around the place, muttering, "This room… it's the Lost Room… I see…"

It's her turn to look down, before the female Ritsuka approaches her, "Hey, calm down, my little eggplant!"

The girl once again startled, this time she nearly stumbles backward as she looks confused, "Wha- who-?"

"Hello!" she waves at her, "I am Ritsuka Fujimaru, but you can call me Gudako. Everyone called me Gudako, in fact."

"Ri- senpai?" the girl turns toward the black-haired teen, who shrugs, "Apparently, she is me from a different world, where I am a girl instead of a dude."

"S-senpai is-"

Gudako quickly grabs her shoulders, pushing her onto her own chair, "Calm down, I said! It's Alternate Reality 101: Every possibility is both a fact and a fiction."

The girl is clearly still confused, looking all over the place before turning toward Olga, "Wha- why are all of you-"

Roman speaks up, "It's good that you are here. We will need all the help we could get for this one."

Olga sighs as she continues, "As I said before, one of the reality was imploded due to the misused of all of Chaldea's inventions, affecting even other realities into it."

"Do you…" Mashu wonders, "Do you want us to help save that reality?"

"Yes," Roman nods, "We were looking for any available Masters from different timelines and realities; from the time where the human order has been saved by them from being burned. You are one of those that answered our call."

Ritsuka (the male one, as what this name will refer to from now onward) turns toward Mashu, "Messages over messages have been entering my email's inbox before, so I thought it was a very urgent one. That is why I entered this place."

Gudako speaks up toward him and Mashu, "It is my reality that is in trouble right now."

"What happened?" the purple-haired girl questioned her.

Gudako is about to answer, but her head turns around toward the door behind her as she stands up, "I'm sorry, but she's here!"

She then turns toward Roman, "Please explain what happened to them. I'll be going out now."

The orange-haired girl runs out of the room, leaving Mashu looking at her, concerned.

Olga clicks her teeth with her tongue, "If only I am still around there to help…"

Roman shakes his head, "I'm sorry, but it seems I also have to get out of here. Even with her own Servant, both of them are still powerless by themselves."

He stares at the two, "It is better if you see it for yourself. Will you accept our call for help?"

"Yes!" Ritsuka nods, agreeing toward him.

Mashu follows him, with words coming out from her, "Then, you should tell us where we should rayshift-"

"No need," he speaks up, "This room is already capable of doing that."

"H-how?"

"That door," he points out toward the door behind the two, "If using normally, you will return back to your own world. But, if I open that door and leave it open, you can reach into my world with the need to rayshift. This is how the Lost Room has been working."

"But…" Ritsuka questions him, "How are we going to return home then?"

"Well… we'll cross that line later, okay?" he gives them a smile as he stands up, moving toward the door and opens it up.

"Now, please go through this door."

Both Ritsuka and Mashu turn toward each other, nodding as they obey his words, moving through the entrance together.

Roman is about to join them before Olga calls out to him, "Are you sure they can save our world?"

He turns toward her, smiling at her, "What are you talking about? They saved humanity before, and the will do again in the future. What's one more, right?"

He then walks through the gate, leaving her as she sighs.

"Maybe I should return back to my time now…"

Xxxxxxxxxxxxxxxxxxx

The two keeps on walking, exiting the room as they see Roman running past them.

The man stops before turning toward them, "Come, you two. We're going to the CHALDEAS."

The three run forward, moving through the corridor, and along the corridor Ritsuka takes this chance to turn his head, taking a look at the outside via a window.

He sees darkness, with nothing outside, not even snow that covers the place constantly.

No, he sees a plain field across as far as the eye can see, with nothing but darkness out there.

The only thing that lights up the outside view is a huge light above them; an unknown light he could not see from here.

"Senpai…" Mashu notices as well, looking at him, "What happened out there?"

"I don't know, Mashu," he mutters, "Perhaps this is a lot worse than I thought."

The three finally reach their destination, with Roman goes toward the console, pressing buttons before the computer and looks around toward the staffs, "Everyone, what's the status?"

"Gate #1 is leaking with enemies!"

"Gudako and Shielder are fighting them outside, sir!"

Before them, a huge holographic screen pops up.

Xxxxxxxxxxxxxxxxxxxx

The outside of this Chaldea is vastly different from most other realities.

Chaldea's building is located in the middle of the vast space, right on top of ground looking like a giant tree.

The building is on the 'root of the tree', and on the edge of the 'branches' are huge door-looking gates, with nothing on the other side of them and chains and locks all around them.

The 'branches' are too many that some of them almost intersecting onto each other, only separated by them moving up or down.

One of the gates is already opened, as some of the skeletal creatures are nearby them, one by one being beaten by a grey-haired man holding a spear.

The man spins around, smacking those skeletal warriors off, breaking even some of their bones.

Near them is Gudako, standing away from the fight, looking intently at the lone male.

Xxxxxxxxxxxxxxxxx

"That's-!" Ritsuka is shocked, looking at the grey-haired man, "I know who that is!"

"Me too!" Mashu screams out in shock as well, "That's Galahad, one of the Knights of Round!"

"You knew him?" Roman stares toward them, "That's good. At least I do not need to introduce them to you."

Ritsuka wonders, "But… if Galahad is here, what about Mashu of this world?"

Some of the staffs look disturbed.

Mashu looks around, wondering, "Wha- what's happening? Why are all of you being silenced here?"

"Hey, that's Kyrielight, right?"

"She's not her… but…"

"I know… it's hard …"

"It's…" Roman mutters, frowning, "Our Mashu… she…"

"Beast is coming!" one of the staff screams out, startling all three of them.

Mashu responds first, "Beast!? Beast-class Servant is here!?"

Xxxxxxxxxxxxxxxxxxx

Out from the opened gate comes a figure, walking out into the open.

A purple-haired female, wearing scale costume that emphasizes her figure while still not exposing much, moving slowly out as she smiles at the Master and the Servant.

"Hello, senpai. How have you been?"

Xxxxxxxxxxxxxxxxxxx

"M-Mashu!?"

"M-ME!?"

Both outsiders stare toward Roman, who still looks down as he turns his head slightly onto their sight, "This is our Mashu Kyrielight… in this reality, she is a Demi-Servant possessed by a Beast-class Servant, and the reason for our world's state."

"I-" Mashu is still shock, trying to form words, "Wh…at have… I do…ne…."

Xxxxxxxxxxxxxxxxxxx

While Galahad is still fighting, the Beast Mashu walks down from the road, moving closer and closer toward Gudako, still smiling toward her creepily.

"Have you been eating properly?" she smoothly asks the Master, "Did you lost any weight? Is this Servant of yours do anything bad to you?"

"Don't worry," she winks at her, "This world I am creating… it will be completed someday, and when it does, we can finally live together, forever. No magus, no Servants, no human order to be protected. Just you, me, and time rotting away."

Galahad just finishes the last skeleton off, now turning his attention toward her, rushing down and jumps onto her.

Mashu sees this and moves to the side, avoiding his strike and grabs the spear. She pulls him close toward her and pushes him back with a snake appears out from her hand.

The snake bites onto Shielder's shoulder, with him lets the weapon go, moving backward before pulling out the sword on his waist and stabs onto the snake, killing it.

Mashu shoots dark beams toward him, as Galahad quickly deflects the beams with his sword while trying to get close to her.

He kneels and pulls his spear back, now dual-wielding against her, but more snakes coming out of her and start wrapping around his body.

Xxxxxxxxxxxxxxxxx

"We need to save him!" Ritsuka turns toward Roman, begging him, "Can we summon a Servant here?"

The professor shakes his head, "I'm afraid it's not possible. After what this world's Mashu did before, it will take time till FATE can be used once more. What about your Mashu? Isn't she a Demi-Servant as well?"

Mashu looks down, touching her chest with her hands, "I lose Galahad's power after the fight with Goetia before. I don't think I can be of use anymore."

Ritsuka asks him, "Aren't you Solomon? Can't you help her out?"

Roman is startled at him before sighing, "You know that too? I must have been careless…"

He then looks away, "Right now… I'm just Romani Archiman…"

The man suddenly turns toward Mashu, "You are still a Demi-Servant, right?"

"I…" the purple-haired megane ponders, "I believe I still am…"

"Then I have something that might be able to compensate your loss of Servant ability. We have been trying to create this particular thing against our Mashu, but it is still under development."

"What is it?" she asks him.

Xxxxxxxxxxxxxxxx

Galahad eventually breaks free from the snakes, cutting them away with his weapons, returning back to attack B-Mashu (short for Beast Mashu).

He stops and goes for a kick, but she pushes the leg off from her face, now punching him with her own fist, making him fall.

But Galahad quickly pushes himself up once more, striking her downward with his sword, which B-Mashu steps backward, narrowly dodging the attack.

Within her hand, a dark, negative energy is charged up and is shot straight toward him, shooting out a huge beam that moves so fast, dodging it will require A+ rank agility (according to the stats).

In response, Galahad puts up his hand forward, as a cross-shaped shield appears within his hand, along with a magic circle and the entrance to an ancient kingdom, defending himself from the beam.

The beam hits the circle, and upon impact, encompassing the whole kingdom before breaking them all into mere mirages, with the grey-haired Servant is thrown back away from the impact, back to his Master.

"Galahad!" Gudako runs and approaches him, helping him standing on his two feet.

B-Mashu slowly moves forward, grinning wide at her, muttering, "Senpai, I am right here… Why are you looking at him? He is nothing more than a useless Servant. I am much more than that. I am without equal! How can you not look at me?"

She approaches them closer and closer, but as her right leg moves forward, something hits the ground, forcing her to stop.

"Get away from them!"

Beast turns her head to the side, now seeing a mirror image of herself, except now she is wearing something really strange.

This mirror image is wearing a purple bulky costume, closing her body off completely except her bust and her thighs. The lower parts of legs and her hands are being attached to metal white parts. Her back looks bigger for some reason and replacing her glasses are bigger, metal-made visors with translucent light blue mirror.

Mashu is holding out her right hand forward, as if she is aiming a gun toward the enemy. No, she does hold a built-in gun.

In simple term, she looks like a robot. Nope, she IS a robot. This is evidence from her Class, as he sees it, being classed as Cyber.

Ritsuka is right beside her, trying to look away from her as he mumbles to himself, "Dr. Roman, have you been an otaku in this world?"

Somehow his words are heard, as the scientist's voice can be heard screaming from his communication device around his wrist.

"Are you implying those are bad equipment!? Those are Psuedo-Noble Phantasm engineered by the R&D Department of Chaldea as a backup plan against the threats of humanity. It is a pinnacle of the fusion of magecraft and science. You should be proud to have been able to see such thing in action!"

Ritsuka doubts he will ever find these around his Chaldea. If it is, he could not imagine the looks on the representatives of the Clock Tower when they see their beloved magecraft been butchered to this extent.

B-Mashu chuckles at the sight, "A manmade item, trying to fight the mother of all demons? It's funny to see how desperate humanity has become."

The girl then notices Ritsuka, and somehow a blush appears on her face as she stars breathing heavily, glaring back toward Gudako, "Senpai, you brought me another of you? My birthday isn't even here yet. How lovely are you?"

The Cyber-class Mashu grits her teeth, feeling irritated from her words alone as she speaks toward her Master without turning, "Senpai, please stand behind me."

Two cylindrical tubes appear behind her, shooting out green flames as she flies forward toward the Beast Mashu, throwing a punch with her right hand.

B-Mashu steps to the side, evading the attack and pushes her to the side.

But the flame is still on, and this pushes her back toward her, this time letting her throws a kick toward her.

B-Mashu grabs her leg, throwing her close toward Gudako and Galahad as she uses her green flame to stop herself from falling.

Roman's voice is heard, "Listen, Mashu, you are wearing a Pseudo-Noble Phantasm. It works similar to the normal Noble Phantasm, except they already have mana inside them for any attacks. Everything attached to you is a weapon. Use it against her!"

Mashu looks at her hands as she taps onto her right hand. Blade comes out of an opened slot, startling her as she turns back toward B-Mashu.

Galahad stands up, holding onto his spear, "We should work together now."

"Yes!" Mashu shouts in agreement.

The two charge forward, with B-Mashu snickers at them, throwing snakes toward them.

Galahad steps forward, slashing the snakes off with Mashu flies up and toward her, striking her blade onto her other self, only to instead slash a snake in her place.

B-Mashu appears out from the dead snake, grabbing her collar and smashes her palm onto Mashu's chest, throwing her off.

Galahad jumps in, stabbing her straight to the face but B-Mashu smacks the spear off.

Mashu now points her hand toward her, shooting bullets toward her, startling her as she jumps off from them.

She charges another of her beam, shooting them straight before they could move aside.

The two Servants now nod toward each other, with Galahad pulling out his shield once again.

Some parts on Mashu's hands open up as she attaches them onto each other, creating her own white cross shield.

 **"LORD CAMELOT!"**

With a scream, a bigger magic circle appears over both shields, and with that creates an even bigger kingdom that deflects the beam. The beam is then reflected back toward its owner, and breaks to her sides as B-Mashu is saved by an invisible barrier.

The Beast Servant is now grinning wide, as seen as the four of them once the smoke from the impact clears out.

The girl now speaks to them, "Interesting, Senpai. Both of you, together with your Servants, have found a hope. Then, the world I've created is now for all of you to discover. Get in there, and see for yourself the land I've made. Save all of those lost souls and use their powers against me. I will be waiting for you, Senpai…"

She turns her back toward them, flying up toward the tallest gate, and enters the gate before shutting it open, locking and chaining it like the rest of them.

While that happens, the rest of the chains now breaks apart, free from their shackles.

Xxxxxxxxxxxxxxxxx

"Gate #1 has locked itself up. All other gates have opened."

"CHALDEAS is detecting massive signals from 20 of them! They seem like… singularities!"

"20!?" Roman screams in shock, "You mean, there are 20 singularities!?"

Xxxxxxxxxxxxxx

"20?" Mashu overheard them, "Senpai, this is a lot more than what we did before."

"Yeah," Ritsuka nods, "But we don't have a choice. These people are counting on us."

Gudako and Galahad approach them, with the former bows at them, "Thank you for being here. We are in need of more friends for this fight."

"Things are going to be a lot more intense from now onward," Shielder mutters, "I hope we can fight together like earlier."

The four stand there, staring at the gates, and their future adventure.

 **End chapter.**

 **I have a feeling a lot of fans are going to kill me for what I did to Mashu.**

 **Please don't kill me…**

 **I was going to give her a different Servant, but I could not think of anybody perfect for this role. So, I made her into a robot, and give her a new class, all because I want her to be special.**

 **Again, if you want to give me ideas for any Servants to appear next, please do so. The Servants can be canon Servants, myth and historical people yet to be used by Type Moon, alternate realities, crossover characters and even a mashup between crossover characters and Fate.**

 **Do note that I do not know everybody, so… yeah…**

 **Next: The four venture into the first singularity, entering a land of Camelot, ruled by Arthur Alter and his sister/wife, Morgan le Fay. Ally: Dark Knight Mordred. (Yup, we are starting strong this one!)**

 **Note: The singularities may not finish immediately…**

Servant of the Day:

 **Servant:** Mashu Kyrielight **  
Class:** Cyber  
 **Alignment:** Lawful Good

 **Skills:**

Magic Resistance: A

Riding: C

Adaptability: B

True Name Discernment: A+

Independent Manifestation: EX

Mana Recharge: A+

 **Noble Phantasm:**

The Armor for Humanity: Cyber Prototype Armor: B+

Weapons for Savior of Mankind: Interchangeable Weapon System: A+

?: EX


End file.
